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排序方式: 共有1173条查询结果,搜索用时 31 毫秒
71.
Although the extensive use of Aspergillus-active antifungals has been recently associated with an increase in zygomycosis in several cancer centers, the frequency of this opportunistic mycosis began to rise earlier, since the mid 1990s. The reasons for that emergence are unclear. Recent evidence suggests that endosymbiotic bacteria of Rhizopus species produce toxins that enhance fungal pathogenicity. We postulate that, although Zygomycetes appear equally ubiquitous and virulent to Aspergillus, zygomycosis was rare in the past in immunosuppressed patients specifically because of the widespread use of antibacterials in this patient population. Such use may have resulted in inhibition of endosymbiotic, toxin-producing bacteria and led indirectly in attenuation of Zygomycetes virulence. Thus, the growing rates of antimicrobial resistance over the past decade selected for multidrug-resistant endosymbiotic bacteria of Zygomycetes, which could facilitate the emergence of zygomycosis. This hypothesis, if true, will be the first paradigm of modulation of virulence of opportunistic fungi by antibacterials. 相似文献
72.
Stagos D Umstead TM Phelps DS Skaltsounis L Haroutounian S Floros J Kouretas D 《Free radical research》2007,41(3):357-366
Surfactant protein-A (SP-A) is the best studied and most abundant of the protein components of lung surfactant and plays an important role in host defense of the lung. It has been shown that ozone-induced oxidation of SP-A protein changes its functional and biochemical properties. In the present study, eight plant polyphenols (three flavonoids, three hydroxycinnamic acids, and two hydroxybenzoic acids) known as strong antioxidants, were tested for their ability to inhibit ozone-induced SP-A oxidation as a mechanism for chemoprevention against lung damage. SP-A isolated from alveolar proteinosis patients was exposed to ozone (1 ppm) for 4 h. The flavonoids protected SP-A from oxidation in a dose dependent manner. ( - )-Epicatechin was the most potent flavonoid and exhibited inhibition of ozone-induced formation of carbonyls by 35% at a concentration as low as 5 μM. Hydroxybenzoic acids inhibited SP-A oxidation in a dose-dependent manner although they were less potent than flavonoids. On the other hand, hydroxycinnamic acids exhibited a different inhibitory pattern. Inhibition was observed only at medium concentrations. The results indicate that inhibition of SP-A oxidation by plant polyphenols may be a mechanism accounting for the protective activity of natural antioxidants against the effects of ozone exposure on lungs. 相似文献
73.
Kararizou EG Manta P Kalfakis N Gkiatas KA Vassilopoulos D 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》2007,29(3):148-152
OBJECTIVE: To determine the morphologic and the morphometrical features of spindles in biopsies of patients with different types of muscular dystrophy and investigate the possible involvement of the spindle in the pathologic process of these diseases. STUDY DESIGN: The following variables were studied in biopsy specimens from 10 patients with Duchenne or Becker dystrophy, 9 with limb-girdle dystrophy, 3 with congenital dystrophy and 3 with facioscapulohumeral dystrophy: diameter and area of spindle; thickness of the capsule; number, diameter and area of intrafusal fibers; and number and area of nuclei. RESULTS: The statistical evaluation of the data showed significant differences regarding the thickness of the capsule, which was greater in patients than in controls, while the diameter and the area of the fibers were all smaller in patients than in controls. The area of nuclei of fibers was increased; this was a common feature for all types of muscular dystrophy. CONCLUSION: These findings indicate that the spindle possibly participates in the pathologic process of different types of muscular dystrophies. 相似文献
74.
Oxidative stress biomarkers responses to physical overtraining: implications for diagnosis 总被引:1,自引:0,他引:1
Margonis K Fatouros IG Jamurtas AZ Nikolaidis MG Douroudos I Chatzinikolaou A Mitrakou A Mastorakos G Papassotiriou I Taxildaris K Kouretas D 《Free radical biology & medicine》2007,43(6):901-910
Overtraining syndrome is characterized by declining performance and transient inflammation following periods of severe training with major health implications for the athletes. Currently, there is no single diagnostic marker for overtraining. The present investigation examined the responses of oxidative stress biomarkers to a resistance training protocol of progressively increased and decreased volume/intensity. Twelve males (21.3+/-2.3 years) participated in a 12-week resistance training consisting of five 3-week periods (T1, 2 tones/week; T2, 8 tones/week; T3, 14 tones/week; T4, 2 tones/week), followed by a 3-week period of complete rest. Blood/urine samples were collected at baseline and 96 h following the last training session of each period. Performance (strength, power, jumping ability) increased after T2 and declined thereafter, indicating an overtraining response. Overtraining (T3) induced sustained leukocytosis, an increase of urinary isoprostanes (7-fold), TBARS (56%), protein carbonyls (73%), catalase (96%), glutathione peroxidase, and oxidized glutathione (GSSG) (25%) and a decline of reduced glutathione (GSH) (31%), GSH/GSSG (56%), and total antioxidant capacity. Isoprostanes and GSH/GSSG were highly (r=0.764-0.911) correlated with performance drop and training volume increase. In conclusion, overtraining induces a marked response of oxidative stress biomarkers which, in some cases, was proportional to training load, suggesting that they may serve as a tool for overtraining diagnosis. 相似文献
75.
Hydrogen peroxide inhibits caspase-dependent apoptosis by inactivating procaspase-9 in an iron-dependent manner 总被引:5,自引:0,他引:5
Barbouti A Amorgianiotis C Kolettas E Kanavaros P Galaris D 《Free radical biology & medicine》2007,43(10):1377-1387
Apoptosis represents a physiological form of cell death, the perturbation of which may contribute to the development of several diseases connected with accumulation of unwanted cells or excessive cell loss. We have previously shown that the continuous presence of low concentrations of H2O2 (generated by the action of glucose oxidase) was able to inhibit caspase-mediated apoptosis in Jurkat cells. The main purpose of the present study was to elucidate the exact molecular mechanism(s) underlying this inhibitory action of H2O2. The results presented show that events like outer mitochondrial membrane permeabilization, release of cytochrome c from mitochondria, oligomerization of Apaf-1, and recruitment of procaspase-9 to apoptosomes were taking place normally, but further advancement toward activation of the execution caspases was interrupted when H2O2 was present during the apoptotic process. From the results presented in this work, it emerges that the inhibition of procaspase-9 autoactivation was probably due to the reversible oxidation of sensitive cysteine residues in this molecule. Remarkably, caspase-9 activation and the ensuing caspase cascade proceeded normally in the presence of H2O2 under conditions of iron deprivation, indicating that the inhibition of procaspase-9 activation was an iron-dependent process. Collectively, these results highlighted the potential role of available intracellular iron ions in signaling mechanisms related to apoptotic cell death. 相似文献
76.
Baskal Svetlana Beckmann Bibiana Stahmer Laura Peter Corinna Bohnhorst Bettina Das Anibh Martin Tsikas Dimitrios 《Amino acids》2022,54(12):1611-1619
Amino Acids - We measured free and proteinic concentrations of native and modified amino acids from post-translational modifications (PTMs) and correlated them with the activity of SIRT1 and SIRT3... 相似文献
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80.
Reed E S Harrison Ronald D Gorham Dimitrios Morikis 《Protein science : a publication of the Protein Society》2015,24(5):789-802
As a part of innate immunity, the complement system relies on activation of the alternative pathway (AP). While feed-forward amplification generates an immune response towards foreign surfaces, the process requires regulation to prevent an immune response on the surface of host cells. Factor H (FH) is a complement protein secreted by native cells to negatively regulate the AP. In terms of structure, FH is composed of 20 complement-control protein (CCP) modules that are structurally homologous but vary in composition and function. Mutations in these CCPs have been linked to states of autoimmunity. In particular, several mutations in CCP 19-20 are correlated to atypical hemolytic uremic syndrome (aHUS). From crystallographic structures there are three putative binding sites of CCP 19-20 on C3d. Since there has been some controversy over the primary mode of binding from experimental studies, we approach characterization of binding using computational methods. Specifically, we compare each binding mode in terms of electrostatic character, structural stability, dissociative and associative properties, and predicted free energy of binding. After a detailed investigation, we found two of the three binding sites to be similarly stable while varying in the number of contacts to C3d and in the energetic barrier to complex dissociation. These sites are likely physiologically relevant and may facilitate multivalent binding of FH CCP 19-20 to C3b and either C3d or host glycosaminoglycans. We propose thermodynamically stable binding with modules 19 and 20, the latter driven by electrostatics, acting synergistically to increase the apparent affinity of FH for host surfaces. 相似文献